In ordinary processes for forming black-and white photographic images, a latent image is formed in a silver halide photographic light-sensitive material through imagewise exposure, and the light-sensitive material is then developed with a developing solution containing a common black-and-white developing agent such as hydroquinone, metol, phenidone, etc. The metallic silver formed in the latent image areas is useful as a black-and-white image. Upon development processing, the oxidation product of the developing agent formed is removed from the system as an unnecessary material.
Imagewise formation of a dye utilizing the oxidation product of the developing agent provides an image density which is the sum of the silver density and the dye density, and, as a result, a higher image density can be obtained using a specific amount of coated silver.
Various processes have been proposed directed to reducing the amount of silver. For example, there is a process for forming a silver image and a dye image at the same time using a coupler developer compound having in the molecule a residue which functions as a developing agent and a residue which functions as a coupler capable of coupling with an oxidation product of the former residue to form a dye, thus reducing the amount of coated silver, as described in U.S. Pat. Nos. 3,615,509 and 3,622,629. Also, there is a process for forming a black image using both p-phenylenediamine derivative and phenol or naphthol, or an active methylene compound, as described in U.S. Pat. No. 2,181,944. Furthermore, a black image has been formed using, as a developing agent, 3-aminopyrazolobenzimidazole, and, as a coupler, an active methylene compound as described in West German Pat. No. 1,158,836.
British Pat. No. 492,518 and West German Pat. No. 537,923 disclose a process for forming a black image by mixing couplers commonly used in the currently employed color photographic process which can form yellow, magenta, and cyan dyes, respectively, and conducting color development. Japanese Patent Application (OPI) No. 37539/72 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") discloses a process for forming a dye image and a silver image at the same time by conducting color development in the presence of a color coupler and fixing without removing silver, thus reducing the amount of silver required to be coated. Japanese Patent Application (OPI) No. 42725/77 discloses a process for forming a black image by using an m-aminophenol derivative as a coupler, Japanese Patent Application (OPI) No. 57827/77 discloses a process for obtaining a black image by using a polyfunctional coupler and a polyfunctional developing agent, U.S. Pat. No. 4,126,461 discloses a process for obtaining a black image by using a diffusion resistant resorcinol derivative as a coupler, and Japanese Patent Application (OPI) No. 123032/79 discloses a process for obtaining a black image by using a dihydroxy naphthalene derivative.
However, the foregoing processes have not been capable of being put into satisfactory practical use, since they have several disadvantages, such as (1) that it is difficult to obtain a high image density for the amount of coated silver, (2) that the materials for forming the images are comparatively expensive, (3) that the fastness of the image formed is insufficient, (4) that skin lesions (i.e., poisoning) may occur upon exposure to color developing agent, particularly p-phenylenediamine derivatives, and the like.
Furthermore, in British Pat. No. 1,122,085, a process for forming images comprising a silver image and a dye image by developing with a processing solution containing both a water-soluble 4-alkoxy-1-naphthol derivative and a 1-phenyl-3-pyrazolidinone derivative is disclosed, and it is also described that the combination of a 1-phenyl-3-pyrazolidinone derivative and an alkoxynaphthol has a high development activity and provides high efficiency in the development of silver and the formation of dye, resulting in obtaining a high optical density. However, as illustrated in Examples hereinafter, the alkoxynaphthols described therein are very rapidly oxidized by air in the presence of an alkali to form compounds which are slightly soluble in water, or they form dyes which are insoluble in a processing solution due to self-coupling. When a photographic light-sensitive material is processed in a developer solution containing alkoxynaphthols which are readily oxidized by air as described above, severe fog is formed, or the dyes formed adhere to the light-sensitive material, which are troublesome in practical use.
By incorporating the alkoxynaphthols described above into a photographic light-sensitive material, such degradation of the developer solution due to the oxidation of alkoxynaphthols by air can be prevented only when a fresh developer solution is employed. However, as illustrated in Examples hereinafter, when the alkoxynaphthols described above are used, the compounds dissolve out little by little from the light-sensitive materials and accumulate in the processing solution when the processing solution is repeatedly used. As a result, oxidation by air occurs in the same manner as in the case when the compound is originally added to the developer solution. Thus, the basic problem still occurs even if the alkoxynaphthols are incorporated in the photographic material.